UV-assisted direct ink writing of near-infrared light-responsive shape memory plant-based resin bone scaffold

This study developed a near-infrared (NIR) light-responsive shape-memory plant-based resin bone scaffold via ultraviolet-assisted direct ink writing (UV-DIW) to address limitations in existing acrylated epoxidized soybean oil (AESO) scaffolds, including mismatched glass transition temperature (Tg) with physiological conditions and reliance on external heat sources.

Polydopamine-modified hydroxyapatite (HA@PDA) particles were blended into liquid AESO to prepare four composite inks with HA@PDA mass fractions of 0 % (AESO), 5 % (A5), 10 % (A10), and 15 % (A15). Bone scaffolds were fabricated using UV-DIW technology at 0 °C. The scaffolds implanted in bone defects could achieve remote temperature regulation via NIR irradiation to induce deformation. Mechanical properties, thermal transitions, photothermal performance, shape-memory behavior, and osteogenic activity were systematically investigated.

Increasing HA@PDA content significantly improved the scaffolds' printing accuracy, surface hydrophilicity, photothermal performance, shape-memory properties, and biocompatibility. A15 exhibited uncured resin during tensile tests and was excluded from subsequent analyses. The Tg values of AESO, A5, and A10 approached body temperature. A10 demonstrated optimal performance, achieving 40 °C within 4 min under 1 W/cm² NIR irradiation and a shape recovery rate of 97 % within 16 s.

A10 scaffold exhibited NIR-responsive shape memory properties, enabling minimally invasive implantation through compressed miniaturized configurations and precise shape recovery under targeted NIR irradiation, while retaining post-implantation dynamic reconfiguration capabilities through non-invasive NIR stimulation. The integrated design methodology combines patient-specific design with minimally invasive delivery and remote postoperative control, addressing the limitations of rigid static implants by enabling adaptable bone scaffolds for personalized tissue regeneration.